1,3,5-triazine-2,4,6-triamine phosphate

Long-term toxicity to fish

Description of key information

Melamine is of low subchronic toxicity to developmental fish.

Additional information

Scientifically it is not regarded necessary to conduct long-term toxicity studies in fish. In the acute toxicity studies it could be shown that aquatic invertebrates are more sensitive compared to fish. Therefore, a chronic toxicity study to Daphnia magna was conducted. This study did not reveal any toxic effect up to a concentration of 10 mg/L. Therfefore, a NOEC of 10 mg/L was determined. Nevertheless, some long-term toxicity data for fish exist and need to be mentioned.

As the substance is a salt of phosphate, effects can be read-across from the cation, which is likely to have the more important effects. In biological systems, phosphate is an abundant in cells and body fluids. In ecological terms, because of its important role in biological systems, phosphate is a highly sought-after resource. Thus, read-across from component CAS Reg.-No. 108-78-1, melamine, is justified. All effect values are minimum values as the molar ratio anion:cation equals 1.74.

Nevertheless, three investigations with 2 species of fresh water fish are available. A study on the egg/larvae development of Jordanella floridae (Adema 1982), a study with juvenile rainbow trout (Goodrich 1984) and an egg/larvae developmental study with rainbow trout (Ramusino 1982). The studies of Adema 1982 and Goodrich 1984 with ca. the same reliability and adequacy were used in a weight of evidence approach. The NOEC for the egg/larvae stage is >1000 mg/L, the NOEC of the juvenile fish for 28 d exposure is 1500 mg/L. Both results indicate a low subchronic toxicity to fish.

The study of Ramusino 1982 is considered to be not sufficiently reliable. The NOEC based on mortality is 1000 mg/L. Doubtful histological results, as judged e.g. by the missing dose-response relation, with 125 mg/L producing more, only histologically detected malformed embryos than at 250 or 500 mg/L. This is interpreted by the authors as a "generic effect". No bias control measures were described, which increases the suspicion that an artefact is reported. This study is therefore not included in the weight of evidence approach. Even if the result would not be an artefact, it would not cause a classification of melamine, as effects occurred above 100 mg/L.

In conclusion, in light of the chronic toxicity study to Daphnia magna and the available fish studies on different species an additional chronic toxicity study to fish is scientifically and for reasons of animal welfare not justified.